Generally, a procedure for performing image processing on an image shot by a camera etc. and storing the processed image on a storage medium is, first perform interpolation processing or color processing on the shot image, and then perform image compression processing on the processed image to store the compressed image on a storage medium. However, since processing speeds of respective parts are different from each other, there has been a problem in that the entire processing speed is determined by slower processing.
For this reason, in order to improve the entire processing speed, various technologies have been considered such as a method taking two types of signals from an image sensor, and performing parallel processing on the signals (refer to, for example, Patent Document 1).
Moreover, a code amount at performing compression processing on a shot image differs depending on the types of the image. For example, in a generally used JPEG type of image compression processing, if image compression is performed using an equal scaling factor (that is a compression parameter to be multiplied by a quantization table so that the quantization bit number may be variable), an image having larger high frequency elements will have a larger code amount, and an image having smaller high frequency elements will have a smaller code amount.
If carrying out such variable-length compression, for an electronic camera having a constant memory size, a problem will arise, in that the number of shootable frames differs depending on a shooting image, which makes it impossible to know remaining number of shootable frames.
Thus, as compression processing in an image processing device, in a point of view to easily know the number of remaining frames, in many cases, a fixed length compression is adopted in which adjusting the scaling factor makes one frame amount of compression data substantially constant. In addition, Patent Document 2 discloses an example of configuration of an electronic camera for performing fixed length compression processing.
Moreover, a fixed length compression is also adopted which predicts and adjusts the scaling factor so that the code amount after image compression falls within a predetermined range (for example, refer to Patent Document 3).    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2002-84493    Patent Document 2: Japanese Unexamined Patent Application Publication No. H09-219807    Patent Document 3: Japanese Unexamined Patent Application Publication No. 2001-61148